Carbon Footprint Calculator vs. Daily Tracker
One gives you a number. The other gives you the habit that changes it.
⚖️ The difference in one line
A carbon footprint calculator asks you to estimate a year of your life in about five minutes. A daily tracker asks you for a few seconds at a time, and builds the year out of what actually happened. Both produce a tonnage. Only one of them is still there tomorrow.
Where calculators are genuinely good
A one-off calculator is the fastest way to find out the order of magnitude you are living at. If you have never seen your own number, it is the right first step: it takes minutes, it costs nothing, and it usually corrects at least one badly wrong intuition — most often about flying, or about how little the small visible things matter next to the big invisible ones.
Its weakness is structural rather than technical. It runs on recalled averages — how many flights in a typical year, how much red meat in a typical week — and recall of typical behaviour is exactly the kind of estimate people are worst at. Then it ends. The number goes in a browser tab, the tab closes, and nothing about the next decision has changed.
What a daily tracker does instead
Decarbonr is built for the other half of the problem: the moment of the decision, repeated. Here is what that looks like in the app.
Log a meal by photographing it
The optional AI scanner estimates a meal’s footprint ingredient by ingredient from a photo. Or scan a barcode to pull product data from OpenFoodFacts, the largest open food database, with 2.9M+ products.
Nine transport modes, real factors
Journeys are logged across nine modes using per-kilometre emission factors from the European Environment Agency and the IPCC, with distances auto-calculated from city pairs.
12+ lifestyle categories
Heating, electricity, water, waste, digital and more — each colour-coded by impact, so the categories nobody thinks to log stop being invisible.
Comparison, not just a total
Your footprint is shown against national averages worldwide, and against the 2-tonne annual target aligned with limiting warming to 1.5°C.
Side by side
| One-off calculator | Daily tracker | |
|---|---|---|
| Input | Recalled yearly averages | What you actually did today |
| Time cost | Minutes, once | Seconds, often |
| Output | An annual estimate | A trend, plus per-item numbers |
| Reaches the decision | No — it happens afterwards | Yes — at the meal, the trip, the bill |
| Best used for | Finding your starting order of magnitude | Moving the number and keeping it moved |
This comparison describes the two general approaches, not any specific competing product.
Why the number has to stay visible
Research on carbon labelling points the same way. In two pre-registered choice experiments published in Nutrients in 2025, responsiveness rose as more of the assortment carried a carbon label — and among the group that responded, the effect was still present four months after exposure but not beyond that. Emissions information moves behaviour while it is in view, and fades when it is not.
We wrote that study up in more detail in Carbon labels work at the shelf, not in memory. The short version is the design brief for a tracker: make the comparison broad, and make it recur.
Beyond the total
Decarbonr also translates the number into something less abstract than tonnes: the temperature the world reaches in 2050 if everyone emitted what you do. There is a goal ring that sweeps from red through amber to emerald as you approach the Paris-aligned 2-tonne target, personalised country-specific reduction tips, goals, streaks and achievements, and a built-in library of timelines, explainers, calculators, country data and quizzes.
And it is private by design. Everything is stored locally on your iPhone — no account to create, nothing synced to a server, no analytics profiles, no ads. Decarbonr is a subscription with a free trial; AI photo and barcode scanning is an optional add-on. Available in 90+ languages on iOS 17.6+.
Start with today, not with last year
Free trial · No account · No ads · On-device · iOS 17.6+
Related reading: Research & sources · Track home energy · Track travel · Private, no account